[PATCH] D36896: [TargetTransformInfo] Call target getMemoryOpCost for LoadInst from getUserCost

[Guozhi Wei via Phabricator via llvm-commits]

Carrot created this revision.

In modern processors, memory load is much slower than basic ALU instructions. 
In function TargetTransformInfoImplCRTPBase::getUserCost, TargetTransformInfoImplBase::getOperationCost is called to compute the cost of memory load, and TTI::TCC_Basic is returned, it's different from real world cost.
This patch changes it to call target dependent getMemoryOpCost implementation to compute the cost of memory load.


https://reviews.llvm.org/D36896

Files:
  include/llvm/Analysis/TargetTransformInfoImpl.h


Index: include/llvm/Analysis/TargetTransformInfoImpl.h
===================================================================
--- include/llvm/Analysis/TargetTransformInfoImpl.h
+++ include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -736,6 +736,13 @@
         return static_cast<T *>(this)->getExtCost(CI, Operands.back());
     }
 
+    if (const LoadInst *LI = dyn_cast<LoadInst>(U)) {
+      return static_cast<T *>(this)->getMemoryOpCost(LI->getOpcode(),
+                                       LI->getType(),
+                                       LI->getAlignment(),
+                                       LI->getPointerAddressSpace(), LI);
+    }
+
     return static_cast<T *>(this)->getOperationCost(
         Operator::getOpcode(U), U->getType(),
         U->getNumOperands() == 1 ? U->getOperand(0)->getType() : nullptr);


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